James a



(No Model.)

J. A. HAMER. SCREW CUTTING MACHINE.

Patented Sept. 20, 1892.

l vi cme/wao/ UNITED STATES PATENT ()FFICE.

JAMES A. HAMER, OF READING, PENNSYLVANIA, ASSIGN OR OF ONE-HALF TO CHARLES D. GILHAM, OF SAME PLACE.

SCREW-CUTTING MACHINE.

SPECIFICATION forming part of Letters Patent No. 483,112, dated September 20, 1892.- Application filed December 19, 1891. Serial No. 415,618. (No model.)

To all whom it may concern:

Be it known that 1, JAMES A. HAMER, a citi= zen of the United States, residing at Reading, in the countyof Berks, State of Pennsylvania, have invented certain Improvements in Screw-Cutting Machines, of which the following is a specification.

This invention relates to improvements in screw-cutting heads having levers pivoted thereto which carry the thread-cutters. These levers are commonly arranged to swing in radial planes and to carry cutters of the ordinary formthat is, with the thread out upon one end of the cutter. Owing to the difliculty with which this form of cutter is sharpened when worn a different form having longitudinal grooves upon one face has been used to a limited extent and when properly set has done good work and may be sharpened when required by merely grinding the end.

The main objects of my invention are, first, to enable these longitudinallygrooved cutters to be economically applied to cutterheads adapted originally for the ordinary form referred to, and, second, to so arrange the longitudinally-grooved cutters that, though their grooved faces are held substantiallytangent to the blank, the cutting end will be withdrawn from the work substantially radially, thereby necessitating a minimum movement and insuring prompt action and close and neat work.

A further object is to so form the grooves of the cutter as to avoid all difficulty in properly setting it.

The invention is fully described in connection with the accompanying drawings and is specifically pointed out in the claim.

Figure 1 is a face view of a screwcutting head having my invention applied thereto. Fig. 2 is a separate View of one of the cutterholders and operating-lever detached from the head. Fig. 3 shows the cutting-tool separate.

The levers B may be pivoted at b to a cutter-head A of any desired construction, so as to be operated by a conical sleeve arranged to slide upon the machine-spindle or by other suitable means for the purpose of opening and closing the cutters, which are carried by holders at the forward ends of the levers. The cutters D are fiat plates having longitudinal grooves d formed upon one face, which grooves correspond with the form and size of the thread which it is desired to cut. Instead of having these grooves run parallel with the sides of the cutters, they are at an angle thereto varying with the pitch of the thread for which the cutter, is intended, so that when the cutter is placed in the slot 19 of the holder B the grooves will be properly inclined to the cutting-edge d without requiring any adjustment whatever. The holders B, forming the heads of the pivoted levers B, as represented, are arranged to bring the line of the slots 19 at about an angle of forty five degrees to the plane in which the lever B, by which it is carried, swings. The cutters are adjustably secured in said slots by means of set-screws f and g, the latter of which serve to regulate the position of the cutting-edge d of the tools longitudinally, while the former serve to clamp the same. Different thicknesses of liners e are provided for cutters adapted to out different numbers of threads to the inch, thus enabling them to be readily set for correspondingly different diameters of bolts, slightly-varying diameters with the same thread being secured by merely adjusting the set-screws g. The cutters may be quickly set to cut any desired thread by employing standard samples, which are secured to the head and into the threads of which the cutters are set.

The dotted circles at the center of the head represent the diameter of a thread adapted to be cut by the cutters when arranged as represented in Fig. l of the drawings, though the position of the cutting-edges d may be somewhat changed without interfering with their working satisfactorily. It will be noticed that, although the cutter is arranged approximately tangentially to the blank operated upon, the cutting-edges cl are withdrawn radially by the operation of the pivoted levers B, which swing in radial planes, and that they are thus lifted clear of the blank with much less movement than if withdrawn in the same plane that the cutters are arranged. Moreover, by this means these 1on What I claim is- In a die stock or head, the combination, with the pivoted cutter levers arranged to swing in radial planes, of the longitudinallygrooved cutters fixed to said levers with their grooved faces at an angle to said radial planes, substantially as and for the purpose set forth.

In testimony whereof I aifix my signature in presence of two witnesses.

JAMES A. HAMER.

Witnesses.

ED. A. KELLY, HENRY B. HINTZ. 

